1. Field of the Invention
The present invention relates to a light-emitting diode such as a light-emitting diode for general lighting, a light-emitting diode for flashlight used in cameras and cellular phones, and a light-emitting diode for key illumination.
2. Description of Related Art
With the reduction in size of electronic devices, light-emitting diodes (hereinbelow abbreviated as LEDs) used in such electronic devices and the like are required to be further reduced in size and thickness. Surface-mount-type LEDs are often used as such LEDs and are generally composed of: an insulating substrate having electrode patterns formed on a surface thereof; a light-emitting element mounted on the substrate; and a light-transmitting resin that seals the light-emitting element. When such an LED is used with its front surface facing down and disposed in a motherboard, the light-transmitting resin is inserted in a hole which is provided in and penetrating the motherboard, and the upper peripheral edges of the substrate of the LED is bonded to the periphery of the hole of the motherboard (see, for example, pages 3 and 4 and FIG. 4 of Japanese Patent Application Laid-Open No. 2001-77430).
A detailed description of an example of an LED mounted on a motherboard will be given with reference to FIG. 7. The LED 40 includes: a light-transmitting substrate 41 having a substantially rectangular parallelepiped shape; a pair of electrodes 42 and 43 each extend from the upper surface to the lower surface via left or right side surface of the light-transmitting substrate 41, the electrodes being formed by vapor deposition, etching, printing, plating, or the like; a light-emitting element 45 electrically connected to the electrodes 42 and 43 through metal wires 44; and a light-transmitting resin 46 that covers and seals the light-emitting element 45 and the metal wires 44. Note that the light-emitting element 45 is bonded to the light-transmitting substrate 41 with a transparent adhesive 48 containing a fluorescent agent 47 included therein.
A motherboard 50 on which the LED 40 is to be mounted has a hole 51 in which the light-transmitting resin 46 is to be inserted. To mount the LED 40 on the motherboard 50, the light-transmitting resin 46 is inserted into the hole 51 with the LED 40 upside-down, and the upper peripheral edges of the light-transmitting substrate 41 are placed on the motherboard 50. Then, the electrodes 42 and 43 are secured to electrode patterns 52 and 53, respectively, provided on the motherboard 50 with solder 54.
The LED 40 has a structure in which light-shielding electrodes 55 and 56 are provided on the entire upper surface of the light-emitting element 45, and thus, the light-shielding electrodes 55 and 56 shields light emitted from an upper surface of the light-emitting element 45. Therefore, the light reflected from the light-shielding electrodes 55 and 56 is emitted downwards (in upward directions in the sheet of FIG. 7) from the lower surface of the light-transmitting substrate 41 through the transparent adhesive 48 containing the fluorescent agent 47 and then illuminates above the motherboard 50.
However, in the above conventional LED, a part of light emitted from the light-emitting element, particularly the light emitted horizontally from a junction of the light-emitting element, may pass through the light-transmitting resin and could leak below the motherboard.